The present invention relates to antimicrobially active nonwoven web incorporating polyhexamethylene biguanide hydrochloride as the antimicrobial in the web, to wet wipers containing such a web, and to a method of making a web. 2. Description of the Related Art
Wet wiper products, including those utilizing non-woven and air-laid webs, require antimicrobial properties to destroy or inhibit the growth of various microorganisms, bacteria, yeast and molds. Several methods are known for treating the fabric of the web wiper product with an antimicrobial agent, but all suffer from various deficiencies.
Antimicrobial surface treatment of a fabric may be beneficial in the dry mode of usage, where microorganisms are either filtered out and/or killed upon contact with the surface of the fabric. U.S. Pat. No. 4,643,181 to Brown provides antimicrobial containing adhesive dressings, in which an antimicrobial agent such as polyhexamethylene biguanide hydrochloride is mixed with a solvent and applied to the outer, skin-contact portion of the adhesive. U.S. Pat. No. 4,655,756 to Fawkes disclosed a non-woven material superficially coated with a linear polymeric biguanide such as polyhexamethylene biguanide dihydrochloride. However, in the case of wet wipers, surface treatment of the fabric has been shown to be insufficient to obtain other necessary microbiological control. The liquid or lotion phase of the wet wiper product penetrates into the interstices of the fabric to carry the microorganisms past the treated surface into the interstices of the fabric, where they may grow and multiply.
Another disadvantage of the surface-treated wet wiper is that the antimicrobial agent leaches out from the fabric and leaves an irritating residue on the user's skin. Many individuals exhibit adverse reaction to such agents, and hence, their enjoyable use of the wet wiper product is significantly impeded.
To overcome these problems, an antimicrobially active nonwoven web for use in wet wipers was developed. (U.S. Pat. No. 4,615,937 and 4,692,374, both to Bouchette) The antimicrobial was applied to a binder which, in turn, was applied to an unbonded fibrous web so that the antimicrobial agent remained substantive to the fibers of the web and to the binder. The typical antimicrobial agent used was an organo-silicon quaternary ammonium salt, such as a silylquaternaryl ammonium salt.
However, it is an object of the present invention to provide an antimicrobially active non-woven web incorporating an antimicrobial agent that is substantive to the web and binder, which exhibits improved antimicrobial activity, a better rate of kill and improved efficacy at lower concentrations (i.e., lower than 0.25% by weight). It is also an object of this invention that the antimicrobial agent be substantive to the web and binder so that it does not leach out and cause irritation to users.
It is still another object of the present invention to provide an antimicrobially active wet wiper which demonstrates excellent aesthetic properties such as low tackiness and good wetting capabilities, and further, exhibits excellent stability and is substantially insensitive to chemical interference.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the combinations particularly pointed out in the appended claims.